Adverse food reactions are common in the general population. Nevertheless, our knowledge of the structure of food allergens and of the mechanisms involved is poor. In 1995 the European Academy of Allergology and Clinical Immunology suggested a classification based on the causative pathogenic mechanism. According to this classification, non-toxic reactions can be divided into food allergies when they recognize immunological mechanisms and food intolerance when there are no immunological implications. The treatment of food intolerance is avoidance of the particular food. There are specific treatments for some food intolerance (beta-galactosidases for the management of lactose intolerance).